JPH09-322441A discloses a stator for a brushless motor. According to the above document, an armature includes a core member that is made of a plurality of ring shaped yoke members that can be separated in an axial direction. Each one of the yoke members has an integrally formed with a tooth portion protruding toward radial outside.
However, the brushless motor disclosed in the above document is an outer rotor type motor. The document discloses nothing about an inner rotor type motor, such as a stator, a brushless motor and manufacturing method for the same. If the yoke disclosed in the above document is modified to fit the inner rotor type motor, the tooth portions have to be arranged to protrude toward radial inside. In the above case, it is hard to wind coils on the tooth portions, especially from a radial outside. It is also difficult to use a flyer winding machine, since the arrangement of the above mentioned core requires to wind a coil from a radial inside. In the above case, it may be still possible to use a nozzle winding machine which can wind a coil on the tooth portion from a radial inside. In a case of using the nozzle winding machine, it is necessary to keep space which allows to move and to pass the nozzle between the tooth portions. In addition, the space lowers the space factor of the coil that is a ratio of a conductive material in a cross section of the coil. As a result, it is difficult to increase the space factor and it makes it difficult to make the rotary electric machine small. In addition, since the nozzle winding machine is slower in a winding speed compare to the flyer winding machine, it is difficult to increase a winding speed of the coil. Additionally, since it is difficult to reduce the number of winding machine, it is difficult to lower cost of products.
In the above discussion, the flyer winding machine includes a flyer and a variable former. The flyer winding machine performs a flyer winding method in which the coil is wound on the tooth portion by feeding the coil from the flyer while driving the flyer to rotate around the tooth portion along a circular path, and, simultaneously, by forming and shaping the coil by using the variable former. The nozzle winding machine includes a nozzle. The nozzle winding machine performs a nozzle winding method in which the coil is wound on the tooth portion by feeding the coil from the nozzle while alternately repeating a rotational driving process for driving the nozzle to move around the tooth portion and a axial sliding process for driving the nozzle to move along the axial direction in a sliding manner.